1. Field of the Invention
This invention relates to coating compositions comprising a polyol, a polyether polyol and an aminoplast and in particular relates to coating compositions comprising a primary polyol, a polyether polyol and a substantially fully etherified substantially completely methylolated polyaminotriazine.
2. Description of the Prior Art
Coating compositions comprising hydroxy polyesters and similar hydroxy containing oligomers and polymers and aminoplast curing agents are well known in the prior art. Thus, U.S. Pat. Nos. 3,449,467 and 3,668,276 disclose organic solutions of hydroxy polyesters of moderately high molecular weight, containing aminoplasts and U.S. Pat. Nos. 3,852,375, 3,920,595 and 3,959,201 disclose high solids coating compositions comprising blends of hydroxy polyesters of moderately low molecular weight and aminoplast curing agents. However, in general these compositions are cured at temperatures well in excess of 100.degree. C. and encompass enormously wide ranges of hydroxy polyester to aminoplast. Moreover, they are generally high in viscosity and therefore require some water or solvent to reduce the viscosity to a level adequate for coating applications. Coating compositions of suitable viscosity for coating applications may be prepared from monomeric polyols and aminoplasts. However, many such compositions, when they are applied to substrates, tend to crawl and form coatings of non-uniform thickness, and also tend to form craters and "orange peel" defects when they are cured.
A need, therefore, exists for a high solids coating composition substantially free of solvent to provide high film build per application, to reduce volatile pollutants evolved during the baking cycle and to improve the economics of the coating process.
A need also exists for a high solids coating composition which can be cured at lower temperatures, for example in the temperature range of 70.degree. to 105.degree. C., thus reducing the energy requirements for the curing process.
A need also exists for a high solids coating composition to provide smooth glossy films, which are free from the problems of crawling, cratering, pin hole formation and orange-peel formation.
A need also exists for a high solids coating compositions which can be formulated with hydroxy polyester oligomers and hydroxy acrylic oligomers to provide surface coating compositions which can be cured to provide coatings with good water, solvent and stain resistance.